From 74eb7446eda5e348dbb90981e91e9caf54f2fde4 Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Tue, 18 Jun 2019 09:37:47 +0800 Subject: scsi: pmcraid: use sg helper to iterate over scatterlist Unlike the legacy I/O path, scsi-mq preallocates a large array to hold the scatterlist for each request. This static allocation can consume substantial amounts of memory on modern controllers which support a large number of concurrently outstanding requests. To facilitate a switch to a smaller static allocation combined with a dynamic allocation for requests that need it, we need to make sure all SCSI drivers handle chained scatterlists correctly. Convert remaining drivers that directly dereference the scatterlist array to using the iterator functions. [mkp: clarified commit message] Reviewed-by: Christoph Hellwig Reviewed-by: Bart Van Assche Signed-off-by: Ming Lei Signed-off-by: Martin K. Petersen --- drivers/scsi/pmcraid.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) (limited to 'drivers/scsi/pmcraid.c') diff --git a/drivers/scsi/pmcraid.c b/drivers/scsi/pmcraid.c index e338d7a4f571..286cac59cb5f 100644 --- a/drivers/scsi/pmcraid.c +++ b/drivers/scsi/pmcraid.c @@ -3270,7 +3270,7 @@ static int pmcraid_copy_sglist( int direction ) { - struct scatterlist *scatterlist; + struct scatterlist *sg; void *kaddr; int bsize_elem; int i; @@ -3279,10 +3279,10 @@ static int pmcraid_copy_sglist( /* Determine the actual number of bytes per element */ bsize_elem = PAGE_SIZE * (1 << sglist->order); - scatterlist = sglist->scatterlist; + sg = sglist->scatterlist; - for (i = 0; i < (len / bsize_elem); i++, buffer += bsize_elem) { - struct page *page = sg_page(&scatterlist[i]); + for (i = 0; i < (len / bsize_elem); i++, sg = sg_next(sg), buffer += bsize_elem) { + struct page *page = sg_page(sg); kaddr = kmap(page); if (direction == DMA_TO_DEVICE) @@ -3297,11 +3297,11 @@ static int pmcraid_copy_sglist( return -EFAULT; } - scatterlist[i].length = bsize_elem; + sg->length = bsize_elem; } if (len % bsize_elem) { - struct page *page = sg_page(&scatterlist[i]); + struct page *page = sg_page(sg); kaddr = kmap(page); @@ -3312,7 +3312,7 @@ static int pmcraid_copy_sglist( kunmap(page); - scatterlist[i].length = len % bsize_elem; + sg->length = len % bsize_elem; } if (rc) { -- cgit v1.2.1